At the manufacturing of products having joining connections, it is meanwhile necessary that different materials, their combinations, different material thicknesses or different auxiliary joining parts have to be processed. This requires always an adapted joining device, as for example a setting device, at the manufacturing of motor vehicles. According to a procedure which is no longer up-to-date, rivet setting devices have been exchanged with each other according to the respective requirements for the joining connection to be produced. These different rivet setting devices used the appropriate auxiliary joining part and the respective die to connect the present components with each other.
For achieving here an increased flexibility, a die changer was used which was firmly installed on a C-frame of a setting device, for example according to EP 1 467 836 B1. This die changer consists of a disc-like rotatable arrangement on which two different dies are arranged. According to DE 10 2014 202 729 A1, also rotatable die discs are usable having three or four dies.
The manufacturing of joining connections meanwhile also takes place in production lines for the manufacturing of motor vehicles in which different vehicles are produced. This increases the requirements with respect to the flexibility of the joining devices, as for example setting devices. Further, welding connections are increasingly replaced by punch riveting connections for which also the appropriate setting devices have to be provided. For reducing the effort for a new installation of the setting devices for the manufacturing of all kinds of joining connections in the production line, it is necessary that the setting devices used have more flexibility in their adaptability to different joining connections.
Therefore, DE 20 2014 102 908 U1 discloses a die holder for a plurality of removable dies. This die holder cooperates with the die dome for receiving a removable die of a setting device which is moved to the die holder by means of a robot. The removable die in the die dome of the setting device is locked in the die dome by means of a rotational movement. The die holder provides a form-fit connection with the removable die by means of a lateral slotted die head. This form-fit connection ensures that the die holder can rotate the removable die for at least a quarter turn and thereby unlock in the die dome of the setting device. At the same time, by means of this rotation, the removable die is locked in the die holder axially. Now, die holder and die dome of the setting device are moved with respect to each other so that the removable die can be removed from the die dome of the setting device. In reversed order, the inserting of another removable die from the die holder into the die dome of the setting device occurs.
The die holder of DE 20 2013 011 927 U1 also receives a removable die from a die dome by means of a rotational movement. This rotational movement of the removable die, which is introduced into the removable die via the die head, requires specific gripping or connection mechanisms that support this rotational movement. Further, a sufficient accuracy at the combined rotational movement and the subsequent linear unlocking or releasing movement of the removable die are necessary which is on the one hand costly in its construction and which requires later high maintenance efforts. With respect to the maintenance, the contamination by and the removing of adhesive residues is, beside others, critical.
As has been mentioned above already, the removable dies are locked in the die dome by means of a combination of a linear movement and a rotational movement or they are withdrawn or removed from the die dome by means of a reversal of these movements. For this purpose, the removable die comprises a locking groove in its die shaft into which the webs of the die dome can engage. These webs are for example arranged oppositely to each other and are firmly installed in the die dome. To be able to insert the die shaft between these webs, it is formed tapered in a certain angular orientation. After rotating the removable die, the tapered shaft portion is oriented perpendicular with respect to the webs so that the die shaft is fixed in the die dome. The insertion depth of the die shaft as well as the rotation angle of the removable die have to be adapted precisely to the removable die to be able to establish a reliable connection between the die dome and the removable die also upon repeated inserting and removing of a removable die. Further, bayonet-like connections between removable die and die dome are disclosed. These are not only susceptible due to the complex movement sequences for locking and unlocking the die in the die dome but also due to a contamination which may deposit in the bayonet connection.
For being able to differentiate the several removable dies stored in the die holder, DE 20 2013 011 928 U1 describes an identification code arranged at the die head or at the die shaft. This identification code is especially arranged at the radially outer side of the die head or the die shaft. Although this identification code, like a bar code, a number code or a two-dimensional code, is detectable by a camera, a scanner or another suitable sensor, these identification codes are susceptible to damaging. Because a rotational movement occurs upon the take-over or receipt of the removable die by the die holder during which the die holder engages at the radially outer side of the die head. During this movement, the identification codes arranged at the die head are damaged. The identification codes arranged at the die shaft are stressed by a frictionally engaged connection of the die shaft at the radially inner side of the die dome. This frictional engagement leads also to a damaging of the identification codes so that the identification codes cannot be read or are not identifiable anymore after several changes of the removable die.
It is, thus, the object of the present invention to provide a die changer with a removable die adapted thereto and an adapted die dome which has, with the same flexibility, a lower susceptibility to failures and, thus, a higher lifetime compared to the prior art. The same applies also to the used removable dies so that they are usable for a higher number of changing cycles without that a damaging in the fixing mechanism and/or in the identification of the removable die occurs. Further, it is an object of the present invention to provide a simplified method for removing a removable die from a die dome of a joining device as well as a simplified method for inserting a removable die into a die dome of a joining device.